With increasing shortage of global energy resources and increasing environmental pollution, clean and renewable energy resources, especially wind energy sources, have been rapidly developing. Wind turbines have gained attention in this regard.
It is known that the operation of a wind turbine depends on the wind speed. For example, wind turbines have predetermined wind speed threshold values for determining operational conditions of a wind generation system. One such threshold value is a cut-in wind speed that is defined as the wind speed when the wind generation system starts to generate power. Another threshold value is a cut-out wind speed which is defined as the highest wind speed when the wind turbine may be operated while delivering power. Normally, generating power will be stopped at wind speeds higher than the cut-out wind speed.
Based on IEC (International Electro-technical Commission) standard, the wind zone is divided into four classes: class I (in which the average wind speed is in the range of 8.5 m/s to 10 m/s), class II (in which the average wind speed is in the range of 7.5 m/s to 8.5 m/s), class III (in which the average wind speed is in the range of 6.0 m/s to 7.5 m/s) and class IV (in which the average wind speed is lower than 6.0 m/s). In the past, most technical developments have been in the medium and high wind.